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Abstract:

The invention relates to a method for thermochemically converting organic
waste material having high molecular weight into liquid combustible
materials and fuels, comprising the following steps: feeding organic
waste material into a reactor, heating the organic waste material to a
temperature between 250° C. and 500° C. while avoiding
exceeding critical coking temperatures in the reactor, feeding biogenic
substances to the reactor, collecting and condensing the gases and vapors
released from the mixture of organic waste material and biogenic
substances, collecting the condensate and letting phases form, and
removing the phase(s) containing liquid combustible materials and fuels.

Claims:

1. A method for thermochemically converting organic waste material having
high molecular weight into liquid combustible materials and fuels,
comprising the following steps: feeding organic waste material into a
reactor, heating the organic waste material to a temperature between
250.degree. C. and 500.degree. C. while avoiding exceeding critical
coking temperatures in the reactor, feeding biogenic substances to the
reactor, collecting and condensing the gases and vapors released from the
mixture of organic waste material and biogenic substances, collecting of
the condensate and letting form phases, removing the phase or phases
containing liquid combustible materials and fuels.

2. The method according to claim 1, characterized in that the organic
waste material consists of long-chain and/or branched hydrocarbon
molecules.

[0003] The conventional method for catalytically cracking hydrocarbons
having high molecular weight in mineral oil processing is the so-called
FCC method (Fluid Catalytic Cracking). Therein, the reaction is carried
out with a circulating gas fluidized bed. The swirled-up catalyst moves
back and forth between the crack reactor operated at approx. 500°
C. and the regenerator operated at approx. 700° C. In the FCC
method, the educt needs to be completely vaporized in the reactor, before
the crack reactions at the swirled-up catalyst particles can occur. For
not easily vaporizable solid matter having high molecular weight such as
e.g. plastics, tar sands or oil shale, this is not possible.

[0004] If the cracking reactions are carried out at low temperatures below
500° C., the initial substances having high molecular weight are
not completely vaporized anymore, so that they are predominantly in a
liquid phase. However, because of the lower temperatures, very active
catalysts mused be used for increasing the reaction speed. A decisive
problem when using cracking catalysts such as zeolites in liquid phase
reactions is however that they very quickly lose their activity, in
particular because of carbonization reactions. This leads to high
operating costs.

[0005] DE 102 15 679 B4 describes the thermal conversion of substances
having high molecular weight into liquid fuels, wherein the cracking
reactions proceed in a heavy oil liquid phase in a temperature range
between 350 and 500° C. By using a gas flow having hydrogenating
or reducing properties, the autocatalytic effect of the heavy oil
fraction is utilized. Using hydrogenating or reducing gases requires
however increased operating pressures of usually more than 5 MPa.
Further, it has to be noted, when using DE 102 15 679 B4, that the
reaction temperatures need to be sufficiently low, in order that the
containers, pipelines, and heating elements do not coke. Critical coking
temperatures have to be expected above 400 to 450° C., depending
on the substance. In order to avoid coking, the reaction temperatures, in
particular at heated walls, must be below the respective critical coking
temperatures. For temperature-stable hydrocarbons such as plastic and
rubber wastes, distillation residues from mineral oil processing, tar
sands or oil shale, higher reaction temperatures are necessary according
to the method of DE 102 15 679 B4, so that for these hydrocarbons, coking
reactions will strongly impair the technical implementation. Another
drawback of DE 102 15 679 B4 is the necessity to heat the raw material
very quickly. Hence, excessive wall temperatures leading to coking are
there usually inevitable.

[0006] The necessity of excessive reaction temperatures for the mentioned
hydrocarbons to a particular degree also applies to pyrolysis methods,
i.e. purely thermal decompositions, so that there, too, undesired coking
reactions represent a substantial problem for the process.

[0007] In DE 19742266 A1, a method is described wherein plastics together
with biomass can be converted into crude oils: In this method, water is
used as an auxiliary agent (hydrolytic cleavage). Therefore, in this
particular process, very high pressures of approx. 20 MPa are necessary.

[0008] There is therefore a need of a method for cleaving the mentioned
hydrocarbons that takes place at atmospheric pressure, does not need any
addition of catalysts, and can be carried out at reaction temperatures
below critical coking temperatures, wherein organic waste material having
high molecular weight, also including the non-evaporative components, can
be converted into liquid combustible materials and fuels.

[0009] This object is achieved by the method described in the claims. The
sub-claims represent advantageous embodiments of the invention.

[0010] The method according to the invention comprises the following
steps:

[0011] heating the organic waste material having high molecular
weight to temperatures between 250° C. and 500° C.,
preferably between 280° C. and 420° C., particularly
preferably between 300° C. and 400° C., while avoiding
exceeding critical coking temperatures in a reactor or alternatively in a
preheater with subsequent transfer into a reactor,

[0012] adding biogenic
substances,

[0013] cooling the released gas-vapor phase, condensing the
vapor fractions and collecting the generated condensate phases,

[0014]
depositing and separating the generated phases.

[0015] It is not necessary to carry out the individual steps of the method
according to the invention one after the other. These steps may proceed
in a different order or, in particular with a continuous mode of
operation, simultaneously.

[0016] The organic waste material having high molecular weight and the
biogenic substances have to be fed in small pieces. Alternatively, the
waste material, if it is fusible, can be processed in a fused condition.
It has proven advantageous to stir during the conversion or to keep the
material moving in a different way.

[0017] Other measures are for instance inert fluidization gases, if the
materials in the reactor are a solid mixture, or circuit pumps, if the
waste material in the reactor is in a fused flowable condition.

[0018] Surprisingly, it has been found that organic waste material having
high molecular weight, also including the non-evaporative components, can
be converted at atmospheric pressure without addition of catalysts at
temperatures up to 500° C., but below the coking temperatures,
i.e. in most cases below 400° C., into liquid combustible
materials and fuels, if biogenic substances are added. Often,
unexpectedly low reaction temperatures below 350° C. have even
been found, at which most organic waste materials having high molecular
weights would not decompose at all without adding biogenic material.

[0019] Biogenic substances are substances, the origin of which is
biological. These may for instance be all materials containing
hydrocarbons such as cellulose, starch and sugar, for instance straw,
miscanthus, corn, green waste, wood etc., also contaminated wood, and all
materials containing proteins, for instance dried sewage sludge, harbor
slick, meat and bone meal etc. Altogether, in principle nearly all plant
and animal materials and processed products thereof such as paper,
carton, food residues or leather are thus suitable. Surprisingly, the
biogenic substances may even be contaminated for instance by heavy
metals, sulfur or halogens.

[0020] Surprisingly, it has been found that the condensed hydrocarbon
liquid product oils to be used as liquid combustible materials and fuels
are virtually free from disturbing biogenic decomposition products. In
the case of contaminations, as described above, the product oils
surprisingly remain free or nearly free from these contaminations.

[0022] The method according to the invention is explained in more detail
by the flow diagram in FIG. 1.

[0023] The organic waste material having high molecular weight is brought
to temperatures from 250° C. to 500° C., preferably
temperatures between 280° C. and 420° C., particularly
preferably between 300° C. and 400° C. This may take place
in a reactor or in a preheater with subsequent transfer into a reactor.
For this purpose, heating systems of various kinds may be used, such as
electrical heating--for instance by resistance, induction or
high-frequency, burner exhaust gas systems or many others.

[0024] After adding biogenic substances, according to the invention, the
organic waste substances having high molecular weight start cleaving into
shorter-chain liquid fuels in the light and middle oil range.

[0025] These vaporize in the reactor and are guided through the gas-vapor
phase at the top out of the reactor, and their vapor fractions are then
liquefied again by cooling and condensing.

[0027] The biogenic substances themselves pass through pyrolytic
decomposition reactions. The biogenic pyrolysis products generated
thereby during the reaction are normally firstly a solid residue directly
leaving the reactor and not getting into the gas-vapor phase, secondly
escaping gases that do not condense, and thirdly biogenic condensate
phases. Corresponding considerations apply to the above-mentioned
contaminations of the biogenic substances.

[0028] Thus, several immiscible condensate phases are generated that
arrange themselves in the condensate separately on top of each other
according to their densities, and can thus mechanically be separated from
each other in a simple way. This simple separation of the product phases
is particularly advantageous.

[0029] A particular advantage of the method according to the invention is
the fact that even not fully vaporizable organic remnants having high
molecular weight and being solid at room temperature can be processed.

[0030] The special features of the method according to the invention are:

[0031] The method proceeds at atmospheric pressure.

[0032] In the
method, a temperature of 400° C. is normally not exceeded.

[0033]
Catalysts are not required.

[0034] Further auxiliary substances for the
reaction, such as water or gases, are not required.

[0035] The generated
product condensate phases can be mechanically separated from each other
in a simple way.

[0036] The method according to the invention can be carried out as a batch
operation or continuously.

[0037] In the following, the invention is explained in more detail with
the aid of the following example.

[0038] 8 kg of a vacuum distillation residue from mineral oil processing
that is solid at room temperature are provided in a laboratory stir
reactor as hydrocarbon having high molecular weight.

[0039] By means of electrical jacket heating at the reactor, this
substance is heated to 390° C. Then, dried and chopped straw is
continuously added as biogenic substance by means of a conveying screw to
the reactor while stirring all the time. During the straw addition, the
generation and release of vaporizing cleavage products through the
gas-vapor phase is observed, these cleavage products being continuously
discharged at the top out of the reactor and conducted through a cooling
condenser.

[0040] The condensate is continuously collected in a separatory funnel.

[0041] The non-condensing gas phase is discharged through an offtake. In
the separatory funnel, four immiscible liquid phases arranged on top of
each other are collected. Arranged by increasing density from top to
bottom, these are firstly a dark-brown oil phase (condensate phase 1),
secondly a black-brown organic phase (condensate phase 2), thirdly a
red-brown aqueous phase (condensate phase 3), and fourthly a black-brown
organic phase (condensate phase 4).

[0042] Added together, 2 kg straw were added over 2 hours. At the end of
the test, 4.21 kg residue were taken from the reactor. An extractive
analysis shows that this residue consists of 0.72 kg carbonization
residue and 3.49 kg heavy oil residue. In the condensate were collected
4.14 kg phase 1, 0.24 kg phase 2, 0.58 kg phase 3 and 0.09 kg phase 4.
0.74 kg gas balance difference was determined. This non-condensing gas
consists, as a gas analysis shows, approx. in one half of
oxygen-containing cleavage products such as carbon dioxide and carbon
monoxide and in the other half of hydrocarbon cleavage products such as
methane, ethane, propane and butane. The olefins thereof, ethylene,
propylene, and butylene were also found.

[0043] In FIG. 2, a GC-MS analysis of the condensate phase 1 of the
product oil according to the invention and an evaluation table of the
signals is shown. It can be seen that predominantly saturated unbranched
alkanes have been generated, and immediately next to every alkane peak
respectively the associated, in most cases smaller olefin peak can be
seen. Disturbing biogenic cleavage products such as phenol derivatives
can virtually not be found.

[0044] For the GC-MS analysis, a device of the company Agilent, Type
HP5972A is used, the separation column coated with cyanpropylphenol and
polysiloxane, Type ZB1701 is from the company Zebron. The heating rate is
(3° C./min). The temperature program covers the range from
45° C. to 280° C. The internal standard was fluoranthene
(retention time 70.05 min).

[0045] In order to demonstrate the freeness from biogenic remnants in the
hydrocarbon product oil (phase 1), a C14 isotope analysis was carried
out. This resulted in a biogenic C share in the product oil of less than
5%.

[0046] The aqueous phase (condensate phase 3) contains, besides water,
acetic acid as the main component. Further, other water-soluble
oxygen-containing organic components such as formic acid, aldehydes,
ketones, alcohols and acetates can be found therein.

[0047] The two other organic condensate phases, phase 2 and phase 4,
predominantly consist of oxygen-containing ring compounds such as phenol
derivatives. Purely paraffinic hydrocarbons such as n-alkanes cannot be
found there.